docs: def makeLambdaPicklable(lambda_function):
      """Take input lambda function l and makes it picklable."""
      if isinstance(lambda_function,
                    type(lambda: None)) and lambda_function.__name__ == '<lambda>':
          def __reduce_ex__(proto):
              # TODO: argdefs, closure
              return unpickleLambda, (marshal.dumps(lambda_function.__code__), )
          lambda_function.__reduce_ex__ = __reduce_ex__
      return lambda_function